KitchenAid Combination Oven Microwave Code F4 E0: inverter alert in the microwave cavity

What F4 E0 means

On KitchenAid combination microwave-wall ovens like the KOCE500ESS, KOCE507ESS or KOCE900HSS, F4 E0 says there may be a problem with the microwave inverter, or the wiring connected to it. The inverter feeds power to the magnetron in the upper cavity. When it is not working, the microwave side cannot heat food and the display holds the code.

Common causes of F4 E0

Microwave inverter has failed or is unstable
Wiring or connectors to the inverter are damaged
Temporary electrical error that locked the microwave side out

✓ One safe check you can try

1. Cancel and clear the cavity. 2. Turn the oven's breaker off for one minute, then on. 3. Run a thirty-second test with a cup of water and nothing else. 4. If the code returns, leave the microwave off and call us.

! Why to stop there

Inverters store high voltage and can injure even when unplugged
It is a replace-or-repair call that requires measured results
We give you the price in writing first, and the repair has a 30-day warranty

Opening a panel yourself does not automatically cancel a manufacturer warranty, but it can cause accidental damage, and some manufacturers set their own service conditions. Check your warranty terms, or ask us, before deciding.

→Same appliance

Other Microwave codes

SEKitchenAid Over-the-Range Microwave Code SE: Keypad or user interface problem Probe or Insert ProbeKitchenAid Combination Microwave Message "Probe" or "Insert Probe": Seat the meat probe in its jack PUSH or PSHKitchenAid Built-In Microwave Message PUSH or PSH: The oven is waiting for Start Registration ErrorKitchenAid Over-the-Range Microwave Message "Registration Error": Check the home network and try again Sabbath, Sab, 5Ab, or 5A6KitchenAid Built-In Microwave Display Sabbath, Sab, 5Ab or 5A6: Sabbath Mode is on F6 E3KitchenAid Built-In Microwave Code F6 E3: Appliance manager and converter control FC E3KitchenAid Over-the-Range Microwave Code FC E3: Router or Wi-Fi module connection lost F6 E7KitchenAid Combination Microwave Code F6 E7: Manager board for the upper cavity

F4 E0F4 E0 questions

Why does F4 E0 name only the inverter when F1 E5 adds the magnetron?

F1 E5 names the inverter or the magnetron tube. F4 E0 names the inverter alone, so a technician starts there with the tests.

Can the oven still do convection?

Many combination ovens keep the lower oven working while the microwave is out. Try it briefly, and keep the microwave off.

What should I tell the technician?

Give us the model number printed on the unit, the code, and whether the cavity heats at all. This helps us bring the inverter part on the first visit.